Seventeen schools in Edinburgh remain closed for a second day due to building safety fears.

Here, we answer the key questions about the closures.

What is wrong with the schools?

The problems were first discovered in January when a wall blew off Oxgangs Primary in high winds and a subsequent investigation found serious structural issues with the building's walls.

Edinburgh City Council closed the school and three others within a week, but on Friday, contractors carrying out remedial works at Oxgangs found new problems, raising concerns that all 17 schools built under the same PPP/PFI contract were at risk, resulting in city-wide closures from Monday onwards.

Read more: Sturgeon calls for full inquiry into closure of 17 PPP schools in Edinburgh

Which schools are closed?

The 17 schools were all built or refurbished following a £360 million 30-year deal between the council and a private finance consortium under the Public Private Partnership 1 (PPP1) scheme. They were built by Miller Construction, with Edinburgh Schools Partnership (ESP) - which oversaw the construction - now managing them for the council.

The schools are Braidburn School, Broomhouse Primary, Castleview Primary, Craigour Park Primary, Craigmount High, Craigroyston Primary, Drummond Community High, Firrhill High, Forthview Primary, Gracemount High, Oxgangs Primary School, Pirniehill Primary, Rowanfield, Royal High, St David's Primary, St Joseph's Primary and St Peter's RC Primary.

What is a PPP/PFI contract?

Public Private Partnerships (PPP) and Private Finance Initiatives (PFI) were brought in to build public facilities such as schools and hospitals.

PPP is the term used to describe collaboration between public bodies such as councils and private companies. Under PFI, contractors pay for the construction costs and then rent the finished project back to the public sector.

PFI was widely used by the Labour/Liberal Democrat administration at Holyrood, but was scrapped by the SNP in 2007.

Critics say the scheme costs more in the long term than had the government used taxpayers' money for the projects. Now there are concerns about the safety of all of the projects built under PPP/PFI as a result of the Edinburgh school closures.

Read more: Scottish councils told to check school building safety after shock Edinburgh closures

What is the Edinburgh Schools Partnership?

The £360 million deal to build the PPP1 schools created a consortium called the Edinburgh Schools Partnership (ESP), which includes Miller Construction, Amey and the Bank of Scotland.

It has said it will accept "full financial responsibility for investigating and resolving these issues to ensure that each and every PPP1 school undergoes all necessary remedial work".

What happens next?

A programme of structural surveys at the schools is continuing. The council said early indications suggest the issue that prompted the decision to close Oxgangs has been identified in other buildings but officials are unable to confirm the extent of this.

The council aims to have all primary school and special school pupils back in classrooms by next Tuesday.

The local authority said ''significant work'' has already taken place to make sure the 2,000 pupils in years S4, S5 and S6 affected will be accommodated in high schools in the city.

Senior pupils from Firrhill, Drummond and Royal High schools will be able to return to their own schools on Wednesday as these three schools only had partial refurbishments as part of the PPP1 project.

Read more: Camley's Cartoon on PPP and the Edinburgh school closures

An update for S4, S5 and S6 pupils at Gracemount and Craigmount will be made later on Tuesday, while work continues to identify alternative arrangements for all S1 to S3 pupils in the five high schools.

Scotland's largest teaching union, the Educational Institute of Scotland, has called for a review of all PPP contracts in Scotland, while political parties have also backed an inquiry into the closures.